Publications by authors named "Lounes Chikhi"

Article Synopsis
  • Genomic and ancient DNA data have dramatically changed our understanding of human evolution, particularly with the successful sequencing of Neanderthal and Denisovan genomes.
  • The theory of interbreeding between Neanderthals and Homo sapiens has evolved from skepticism to general acceptance, largely based on statistical models that may overlook the complexities of population structure.
  • Research using simulated data revealed that many existing models inaccurately identified admixture events and emphasized the need to consider population structure for a more accurate understanding of human evolutionary history.
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Species ranges are dynamic, experiencing expansions, contractions or shifts in response to habitat changes driven by extrinsic factors such as climate change or human activities. While existing research examines the genetic consequences of spatial processes, few studies integrate species-specific traits to analyse how habitat changes affect co-existing species. In this study, we address this gap by investigating how genetic diversity patterns vary among species with different traits (such as generation length, population density and dispersal) experiencing similar habitat changes.

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Article Synopsis
  • * The article proposes a comprehensive approach to accurately define species boundaries, using integrated evidence and focusing on geographic isolation, specifically applied to the mouse lemurs, a debated group of primates.
  • * The study reveals that previous estimates of species diversity were inflated, mainly mistaking geographic variation for new species, and suggests that a clearer understanding of species limits can inform better conservation strategies.
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  • * Bushpigs (Potamochoerus larvatus) and red river hogs (P. porcus) were once thought to be the same species due to their morphological differences and lack of interbreeding, but genetic analysis reveals a more complex relationship with evidence of historical gene flow.
  • * The study suggests that instead of being distinct species, bushpigs and red river hogs may represent incompletely speciation, and that Malagasy bushpigs diverged from their southern African relatives during a population bottleneck that coincided with human arrival in Madagascar.
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Madagascar exhibits extraordinarily high level of species richness and endemism, while being severely threatened by habitat loss and fragmentation (HL&F). In front of these threats to biodiversity, conservation effort can be directed, for instance, in the documentation of species that are still unknown to science, or in investigating how species respond to HL&F. The tufted-tail rats genus (Eliurus spp.

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Objectives: The investigation of morphological variation in animals is widely used in taxonomy, ecology, and evolution. Using large datasets for meta-analyses has dramatically increased, raising concerns about dataset compatibilities and biases introduced by contributions of multiple researchers.

Materials And Methods: We compiled morphological data on 13 variables for 3073 individual mouse lemurs (Cheirogaleidae, Microcebus spp.

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Article Synopsis
  • Habitat loss and fragmentation impact different organisms variably, prompting a study on how these factors influence two rodent species—one endemic and one invasive—in Madagascar's fragmented forests.
  • The research used genetic data to assess inbreeding, genetic diversity, and connectivity, revealing higher inbreeding and lower diversity in the endemic species compared to the invasive one.
  • Findings included patterns of relatedness within and between habitat patches, with different migration rates for each species that did not align with the type of habitat they occupied, highlighting potential ecological constraints on the endemic species.
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In tropical forests, anthropogenic activities are major drivers of the destruction and degradation of natural habitats, causing severe biodiversity loss. African colobine monkeys (Colobinae) are mainly folivore and strictly arboreal primates that require large forests to subsist, being among the most vulnerable of all nonhuman primates. The Western red colobus Piliocolobus badius and the King colobus Colobus polykomos inhabit highly fragmented West African forests, including the Cantanhez Forests National Park (CFNP) in Guinea-Bissau.

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Article Synopsis
  • Madagascar's Central Highlands consist mainly of grasslands and forests, with new research indicating that these grasslands may have existed before humans arrived, challenging past beliefs about their origins.
  • A study on Goodman’s mouse lemur was conducted to analyze population genetics and habitat changes, showing that habitat fragmentation occurred naturally due to climatic shifts during the last glacial maximum.
  • Results reveal that while grasslands likely predate humans, human activity has contributed to population declines in species, indicating ongoing vulnerabilities from both historical and current environmental changes.
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The relative contribution of selection and neutrality in shaping species genetic diversity is one of the most central and controversial questions in evolutionary theory. Genomic data provide growing evidence that linked selection, i.e.

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Background: Quaternary climate fluctuations have been acknowledged as major drivers of the geographical distribution of the extraordinary biodiversity observed in tropical biomes, including Madagascar. The main existing framework for Pleistocene Malagasy diversification assumes that forest cover was strongly shaped by warmer Interglacials (leading to forest expansion) and by cooler and arid glacials (leading to forest contraction), but predictions derived from this scenario for forest-dwelling animals have rarely been tested with genomic datasets.

Results: We generated genomic data and applied three complementary demographic approaches (Stairway Plot, PSMC and IICR-simulations) to infer population size and connectivity changes for two forest-dependent primate species (Microcebus murinus and M.

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Quaternary climatic changes have been invoked as important drivers of species diversification worldwide. However, the impact of such changes on vegetation and animal population dynamics in tropical regions remains debated. To overcome this uncertainty, we integrated high-resolution paleoenvironmental reconstructions from a sedimentary record covering the past 25,000 years with demographic inferences of a forest-dwelling primate species (Microcebus arnholdi), in northern Madagascar.

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Inferring the demographic history of species is one of the greatest challenges in populations genetics. This history is often represented as a history of size changes, ignoring population structure. Alternatively, when structure is assumed, it is defined a priori as a population tree and not inferred.

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Genotyping-by-sequencing methods such as RADseq are popular for generating genomic and population-scale data sets from a diverse range of organisms. These often lack a usable reference genome, restricting users to RADseq specific software for processing. However, these come with limitations compared to generic next generation sequencing (NGS) toolkits.

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Many species are structured in social groups (SGs) where individuals exhibit complex mating strategies. Yet, most population genetic studies ignore SGs either treating them as small random-mating units or focusing on a higher hierarchical level (the population). Empirical studies acknowledging SGs have found an overall excess of heterozygotes within SGs and usually invoke inbreeding avoidance strategies to explain this finding.

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Delimitation of cryptic species is increasingly based on genetic analyses but the integration of distributional, morphological, behavioral, and ecological data offers unique complementary insights into species diversification. We surveyed communities of nocturnal mouse lemurs (Microcebus spp.) in five different sites of northeastern Madagascar, measuring a variety of morphological parameters and assessing reproductive states for 123 individuals belonging to five different lineages.

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Article Synopsis
  • Mouse lemurs, a diverse group of tiny primates in Madagascar, have seen a rapid increase in recognized species over the last 20 years, raising concerns about the oversplitting of this group.
  • In a study focusing on an area in northeastern Madagascar, researchers used genetic data to examine two pairs of mouse lemur lineages, discovering significant differences in their populations and genetic structures.
  • The findings support classifying one previously undescribed lineage as a separate species, while questioning the distinction of two other recognized species, indicating rapid evolution and reproductive isolation within these primates.
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Tropical forests harbor extremely high levels of biological diversity and are quickly disappearing. Despite the increasingly recognized high rate of habitat loss, it is expected that new species will be discovered as more effort is put to document tropical biodiversity. Exploring under-studied regions is particularly urgent if we consider the rapid changes in habitat due to anthropogenic activities.

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Background: Iberian primitive breeds exhibit a remarkable phenotypic diversity over a very limited geographical space. While genomic data are accumulating for most commercial cattle, it is still lacking for these primitive breeds. Whole genome data is key to understand the consequences of historic breed formation and the putative role of earlier admixture events in the observed diversity patterns.

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In the last years, a wide range of methods allowing to reconstruct past population size changes from genome-wide data have been developed. At the same time, there has been an increasing recognition that population structure can generate genetic data similar to those produced under models of population size change. Recently, Mazet et al.

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The increasing amount of genomic data currently available is expanding the horizons of population genetics inference. A wide range of methods have been published allowing to detect and date major changes in population size during the history of species. At the same time, there has been an increasing recognition that population structure can generate genetic data similar to those generated under models of population size change.

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We challenge the view that our species, Homo sapiens, evolved within a single population and/or region of Africa. The chronology and physical diversity of Pleistocene human fossils suggest that morphologically varied populations pertaining to the H. sapiens clade lived throughout Africa.

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